The present invention relates to compounds and their uses, and in particular to compounds which have a mimetic or antagonistic property of an inositol phosphoglycan, and the uses of these compounds, e.g. to treat a condition ameliorated by administration of an IPG second messenger or an IPG antagonist thereof.
Many of the actions of growth factors on cells are thought to be mediated by a family of inositol phosphoglycan (IPG) second messengers[13]. It is thought that the source of IPGs is a xe2x80x9cfreexe2x80x9d form of glycosyl phosphatidylinositol (GPI) situated in cell membranes. IPGs are thought to be released by the action of phosphatidylinositol-specific phospholipases following binding of growth factors to receptors on the cell surface. There is evidence that IPGs mediate the action of a large number of growth factors including insulin, nerve growth factor, hepatocyte growth factor, insulin-like growth factor I (IGF-I), fibroblast growth factor, transforming growth factor xcex2, the action of IL-2 on B-cells and T-cells, ACTH signalling of adrenocortical cells, IgE, FSH and hCG stimulation of granulosa cells, thyrotropin stimulation of thyroid cells, cell proliferation in the early developing ear and rat mammary gland.
Partially characterised inositolphosphoglycans (IPGs) have been postulated to mediate the action of a number of growth factors including insulin and insulin-like growth factor I (IGF-I)[1]. Despite their isolation from several tissues type, the precise chemical structures of these IPGs are, however, still unknown and two main structural groups have been proposed on the basis of the chemical composition[2,3] which display different biological activity and tissue distribution[4]; the family of glucosamine-myo-inositol containing IPGs (IPG-A) and the family of chiro-inositol-galactosamine containing IPGs (IPG-P).
In an attempt to establish the minimal structural requirements for biological activity, a number of compounds containing some of the basic structural motifs that have been postulated for IPG mediators have been synthesised in the art[5]. These synthetic compounds include O-(2-amino-2-deoxy-D-glucopyranosyl)-xcex1(1-6)-chiro-inositol 1-phosphate and O-(2-amino-2-deoxy-D-glucopyranosyl)-xcex1(1-6)-myo-inositol 1-phosphate[6].
U.S. Pat. No. 6,004,938 (Hoechst) discloses a group of synthetic inositol glycans having insulin-like action. The compounds are based on 2-6 monsaccharide units linked to an inositol moiety. The examples in the patent all employ myo-inositol and are composed of 5 or 6 units apart from two pseudo-trisaccharide compounds G and H. Compounds G and H are HOxe2x80x94PO(H)O-6Man-xcex1(1-4)-GluN-xcex1(1-6)-(L)inositol-1,2(cyclic) phosphate and HOxe2x80x94PO(H)O-6Man-xcex1(1-4)-GluN-xcex1(1-6)-(L)inositol, otherwise known as O-(6-hydrogenphosphonate-xcex1-D-mannopyranosyl)-(1-4)-(2-ammonio-2-deoxy-xcex1-D-glucopyranosyl)-(1-6)-L-myo-inositol-1,2-cyclic phosphate and O-(6-hydrogenphosphonate-xcex1-D-mannopyranosyl)-(1-4)-(2-amino-2-deoxy-xcex1-D-glucopyranosyl)-L-myo-inositol. The properties of exemplified compounds are investigated in lipogenesis and glucose transport assays employing rat fat cells.
WO96/14075 (University of Virginia) discloses a generic family of compounds D-hexosamines linked to an inositol via a xcex21,4-linkage. The inositols can be myo or chiro-inositol or pinitol, while the hexosamines are glucosamine or galactosamine. However, this application describes the synthesis of just two compounds 4-O-(2-deoxy-2-amino-xcex2-D-galactopyranosyl)-D-pinitol and 4-O-(2-deoxy-2-amino-xcex2-D-galactopyranosyl)-D-chiro-inositol, or in IUPAC notation O-(2-amino-2-deoxy-xcex2-D-galactopyranosyl)-(1-4)-D-pinitol and O-(2-amino-2-deoxy-xcex2-D-galactopyranosyl)-(1-4)-D-chiro-inositol.
WO99/06421 (University of Virginia) describes synthetic insulin mimetic substances and includes a general formula I showing xcex21,4-linked disaccharides. However, despite this the compounds synthesised in this application are exactly the same as those disclosed in the applicant""s earlier application, WO96/14075.
A multi-step synthesis of a IPG-P mimetic from glucose has been previously reported in Jaramillo et al[6], which discloses a compound called C4, 1-D-6-O-(2-amino-2-deoxy-xcex1-D-glucopyranosyl)-chiro-inositol 1-phosphate. A further synthesis of C4 is described in our co-pending International Patent Application PCT/GB99/03715 (Rademacher Group Limited). Zapata et al[16] discloses three other compounds C1-C3 which are:
C1 1-D-4-O-(2-amino-2-deoxy-xcex1-D-glucopyranosyl)-myo-inositol 1-phosphate.
C2 1-D-6-O-(2-amino-2-deoxy-xcex1-D-glucopyranosyl)-myo-inositol 1-phosphate.
C3 1-D-6-O-(2-amino-2-deoxy-xcex1-D-glucopyranosyl)-myo-inositol 1,2 cyclic-phosphate.
It remains a significant problem in the art to produce synthetic compounds which can mimic one or more of the activities of inositol phosphoglycans or which act as antagonists of IPGs.
Broadly, the present invention relates to IPG mimetic and antagonist compounds and to methods of producing the compounds and to their medical uses. The compounds disclosed herein are useful as synthetic mimetics of IPG-P or IPG-A second messengers and/or growth factors whose action is mediated by IPGs, or a competitive antagonists of IPGs In particular, the present invention is based on surprising finding that compounds comprising a sugar residue linked to a cyclitol, wherein the sugar residue is substituted with one or more negatively charged groups, such as phosphate or other phosphoryl groups, have one or more as IPG or IPG antagonists biological activities.
Accordingly, in a first aspect, the present invention provides a compound represented by the general formula:
X-cyclitol
wherein:
X represents a sugar residue;
the sugar residue is substituted with one or more negatively charged groups;
the sugar residue and cyclitol are linked by an xcex1 or xcex2 linkage other than a xcex21,4 linkage;
the sugar residue is optionally further substituted with between one and three groups, and the cyclitol is unsubstituted or is substituted with between one and five groups, the group or groups independently selected from:
(a) phosphoryl groups such as phosphate xe2x80x94Oxe2x80x94P(O)(OH)2; thiophosphate xe2x80x94Oxe2x80x94P(S)(O)2; phosphate esters xe2x80x94Oxe2x80x94P(O)(OR)2; thiophosphate esters xe2x80x94Oxe2x80x94P(S)(OR)2; phosphonate xe2x80x94Oxe2x80x94P(O)OHR; thiophosphonate xe2x80x94Oxe2x80x94P(S)OHR; substituted phosphonate xe2x80x94Oxe2x80x94P(O)OR1R2; substituted thiophosphonate xe2x80x94Oxe2x80x94P(S)OR1R2; xe2x80x94Oxe2x80x94P(S)(OH)(SH); cyclic phosphate;
(b) other phosphorus containing compounds such as phosphoramidite xe2x80x94Oxe2x80x94P(OR)xe2x80x94NR1R2 and phosphoramidate xe2x80x94Oxe2x80x94P(O)(OR)xe2x80x94NR1R2;
(c) sulphur groups such as xe2x80x94Oxe2x80x94S(O)(OH), xe2x80x94SH, xe2x80x94SR, xe2x80x94S(xe2x80x94O)xe2x80x94R, xe2x80x94S(O)2R, ROxe2x80x94S(O)2xe2x88x92, xe2x80x94Oxe2x80x94SO2NH2, xe2x80x94Oxe2x80x94SO2R1R2 or sulphamide xe2x80x94NHSO2NH2;
(d) amino groups such as xe2x80x94NHR, xe2x80x94NR1R2, xe2x80x94NHAc, xe2x80x94NHCOR, xe2x80x94NHxe2x80x94Oxe2x80x94COR, xe2x80x94NHSO3xe2x88x92, xe2x80x94NHSO2R, xe2x80x94N(SO2R)2, and/or amidino groups such as xe2x80x94NHxe2x80x94C(xe2x95x90NH)NH2 and/or ureido groups such as xe2x80x94NHxe2x80x94COxe2x80x94NR1R2 or thiouriedo groups such as xe2x80x94NHxe2x80x94C(S)xe2x80x94NH2;
(e) hydroxy groups and substituted hydroxy groups such as xe2x80x94OR3, where R3 is C1-10 unsubstituted or substituted alkyl, e.g. CHF2 or CF3, alkoxyalkyl, aryloxyalkyl, cycloalkyl, alkenyl (unsubstituted alkyl), alkylene (C3-7 cycloalkyl), xe2x80x94OCOR, aryl, heteroaryl, acetal, or where two hydroxyl groups are joined as a ketal;
(f) halogen substituents such as fluorine or chlorine;
(g) hydrogen, e.g. to provide a deoxy sugar;
wherein R, R1 and R2 are independently hydrogen or C1-10 unsubstituted or substituted alkyl or aryl.
The compounds may be provided as racemic or diasteromeric mixtures, resolved or partially resolved optical isomers, and as pharmaceutically acceptable salts, esters and derivatives as discussed in more detail below.
Examples of groups which may be negatively charged depending on the pH conditions include phosphoryl groups such as phosphate xe2x80x94Oxe2x80x94P(O)(OH)2; thiophosphate xe2x80x94Oxe2x80x94P(S)(OH)2; phosphonate xe2x80x94Oxe2x80x94P(O)OHR; thiophosphonate xe2x80x94Oxe2x80x94P(S)OHR; xe2x80x94Oxe2x80x94P(S)(OH)(SH); cyclic phosphate; or sulphur groups such as xe2x80x94Oxe2x80x94S(O)(OH); or carboxylate groups such as carboxylic acid.
Preferably, the sugar residue is substituted at one or more positions other than the position of linkage to the cyclitol. In embodiments disclosed herein, the sugar residue is substituted at positions 3 and/or 4 and/or 6.
Preferably, the sugar residue is a hexose or a pentose, and may be an aldose or a ketose. The sugar residue can a member of the D or L series and can include amino sugars, deoxy sugars and their uronic acid derivatives. Preferably, where the sugar residue is a hexose, it is selected from the group consisting of glucose, galactose or mannose, or substituted hexose sugar residues such as an amino sugar residue such as hexosamine, galactosamine or glucosamine, and more preferably D-glucosamine (2-amino-2-deoxy-D-glucose) or D-galactosamine (2-amino-2-deoxy-D-galactose). Preferred pentose sugar residues include arabinose, fucose and ribose. The sugar residue is optionally substituted at one, two, three or four positions, other than the position of linkage to the cyclitol moiety.
The cyclitol moiety is preferably selected from myo-inositol, chiro-inositol or pinitol (3-O-methyl-chiro-inositol), in either their D or L forms, and is optionally substituted at one or more of the positions other than the position of linkage to the sugar radical, or in the case of pinitol additionally the 3-position. The sugar radical is optionally substituted at one, two, three or four positions other than at the position of linkage to the inositol moiety (the anomeric position). Where the cyclitol moiety is substituted at the 3-position (e.g. is a pinitol or a related compound), preferably the substituent is C1-10 alkyl, and may be a substituted or unsubstituted primary, secondary or tertiary alkyl group, e.g. CF3. Examples of substituted groups include CF3, X(CH2)nxe2x80x94Oxe2x80x94 (where X is hydrogen, or substituted or unsubstituted alkyl), CHF2Oxe2x80x94. A preferred alkyl group is methyl when the cyclitol is D or L-pinitol (3-O-methyl-chiro-inositol), and is optionally substituted at one or more of the positions other than the 3-position or the position of linkage to the sugar residue. In further embodiments, the cyclitol may have one or more of the hydroxyl groups through which the substituents described above are removed so that any substituent(s) are linked to the ring carbon atom. The sugar residue is optionally substituted at one, two or three positions other than at the position of linkage to the inositol moiety.
Preferably, the linkage position of the sugar residue to the cyclitol is selected from a 1,1 linkage, 1,2 linkage, 1,4 linkage or 1,5 linkage or 1,6 linkage. The linkage between the units is preferably via one of the oxygen atoms of the cyclitol moiety. However, this oxygen atom can be replaced one or more times by xe2x80x94CH2xe2x80x94 or xe2x80x94Sxe2x80x94 groups. In preferred embodiments of the invention, the linkage of the sugar residue to the cyclitol is 1,6 but may be in either the xcex1 or xcex2 configuration.
In a further aspect, the present invention provides a compound represented by the general formula:
X-xcex11,6-cyclitol
wherein:
X represents a sugar residue,
the sugar residue is substituted with one or more negatively charged groups;
the sugar residue and cyclitol are linked by an xcex1 or xcex2 linkage other than a xcex21,4 linkage;
the sugar residue is optionally further substituted with between one and three groups, and the cyclitol is unsubstituted or is substituted with between one and five groups, the group or groups independently selected from:
(a) phosphoryl groups such as phosphate xe2x80x94Oxe2x80x94P(O)(OH)2; thiophosphate xe2x80x94Oxe2x80x94P(S)(OH)2; phosphate esters xe2x80x94Oxe2x80x94P(O)(OR)2; thiophosphate esters xe2x80x94Oxe2x80x94P(S)(OR)2; phosphonate xe2x80x94Oxe2x80x94P(O)OHR; thiophosphonate xe2x80x94Oxe2x80x94P(S)OHR; substituted phosphonate xe2x80x94Oxe2x80x94P(O)OR1R2; substituted thiophosphonate xe2x80x94Oxe2x80x94P(S)OR1R2; xe2x80x94Oxe2x80x94P(S)(OH)(SH); cyclic phosphate;
(b) other phosphorus containing compounds such as phosphoramidite xe2x80x94Oxe2x80x94P(OR)xe2x80x94NR1R2 and phosphoramidate xe2x80x94Oxe2x80x94P(O)(OR)xe2x80x94NR1R2;
(c) sulphur groups such as xe2x80x94Oxe2x80x94S(O)(OH), xe2x80x94SH, xe2x80x94SR, xe2x80x94S(xe2x80x94O)xe2x80x94R, xe2x80x94S(O)2R, ROxe2x80x94S(O)2xe2x88x92, xe2x80x94Oxe2x80x94SO2NH2, xe2x80x94Oxe2x80x94SO2R1R2 or sulphamide xe2x80x94NHSO2NH2;
(d) amino groups such as xe2x80x94NHR, xe2x80x94NR1R2, xe2x80x94NHAc, xe2x80x94NHCOR, xe2x80x94NHxe2x80x94Oxe2x80x94COR, xe2x80x94NHSO3xe2x88x92, xe2x80x94NHSO2R, xe2x80x94N(SO2R)2, and/or amidino groups such as xe2x80x94NHxe2x80x94C(xe2x95x90NH)NH2 and/or ureido groups such as xe2x80x94NHxe2x80x94COxe2x80x94NR1R2 or thiouriedo groups such as xe2x80x94NHxe2x80x94C(S)xe2x80x94NH2;
(e) hydroxy groups and substituted hydroxy groups such as xe2x80x94OR3, where R3 is C1-10 unsubstituted or substituted alkyl, e.g. CHF2 or CF3, alkoxyalkyl, aryloxyalkyl, cycloalkyl, alkenyl (unsubstituted alkyl), alkylene (C3-7 cycloalkyl), xe2x80x94OCOR, aryl, heteroaryl, acetal, or where two hydroxyl groups are joined as a ketal;
(f) halogen substituents such as fluorine or chlorine;
(g) hydrogen, e.g. to provide a deoxy sugar;
wherein R, R1 and R2 are independently hydrogen or C1-10 unsubstituted or substituted alkyl or aryl.
In preferred embodiments, the present invention provides a compound, or a substituted forms and derivatives thereof as defined above, selected from the group consisting of:
RGL1023 O-(2xe2x80x2-amino-2xe2x80x2-deoxy-6xe2x80x2-phosphate-D-glucopyranosyl)-xcex1(1,6)-D-myo-inositol.
RGL1027 O-(2xe2x80x2-amino-2xe2x80x2-deoxy-4xe2x80x2-phosphate-D-glucopyranosyl)-xcex1(1,6)-D-myo-inositol.
RGL1029 O-(2xe2x80x2-amino-2xe2x80x2-deoxy-3xe2x80x2-phosphate-D-glucopyranosyl)-xcex1(1,6)-D-myo-inositol.
RGL1105 1xe2x80x3-D-4xe2x80x2-O-(6xe2x80x3-phosphate-xcex1-D-mannopyranosyl)-[1xe2x80x2-D-6-O-(2xe2x80x2-amino-2xe2x80x2-deoxy-xcex1-D-glucanopyranosyl)-myo-inositol].
RGL1115 1xe2x80x2-D-6-O-(2xe2x80x2-amino-2xe2x80x2-deoxy-xcex1-D-glucanopyranosyl)-5-O-phosphate-myo-inositol.
In a further aspect, the present invention provides methods for making the compounds of the invention or their intermediates as set out in the following experimental description and the schemes. In a further related aspect, the present invention further relates to compounds which are the novel intermediates described herein.
In a further aspect, the present invention provides one or more of the above compounds for use in a method of medical treatment. The compounds may be useful as IPG mimetics or IPG antagonists, e.g. competitive antagonists.
In a further aspect, the present invention provides the use of one or more of the above compounds for the preparation of a medicament for the treatment of a condition ameliorated by the administration of an inositol phosphoglycan (IPG) second messenger or an IPG antagonist. Examples of such conditions are set out in the pharmaceutical uses section below.
In a further aspect, the present invention provides a method of treating a condition in a mammal ameliorated by an inositol phosphoglycan (IPG) second messenger or an IPG antagonist, the method comprising administering to the mammal a therapeutically effective amount of one or more of the above compounds.
Embodiments of the invention will now be described by way of example and not limitation with reference to the accompanying drawings.